Holbay engine - which dizzy ?

Paul Goldsmith

Paul Goldsmith

0
Looking to go for an electronic dizzy on the rebuilt Holbay for Hunny, on her existing Commer 1725 she's got the SimonBBC full electronic dizzy setup.

I'm not sure whether this will be a good straight swap to the Holbay as I don't believe this engine runs any vacumn advance. Can anybody advise whether this is correct and if so what electronic dizzy I could use on the Holbay ?

Cheers

HolbayLogo.jpg

'Hunny' our Commer Hi-Tor by TorCars
 
Isnt it a lucas25d4 dizzy in the holbay? Just get the number off the side and buy an electronic ign to fit.;)
Actually i think its a 23d4 dizzy?
 
Thanks Jon, I'll recheck the WM tonight but think it's the 23D4 as you say

It all seemed straightforward but then I looked online at 'leccy options and they appeared to vary for different applications / advance curves etc. Hence my confusion, being non-technical but a keen learner !

HolbayLogo.jpg

'Hunny' our Commer Hi-Tor by TorCars
 
I don,t think you want an electronic dizzy Paul, these are very expensive, i assume you mean an electronic ignition.
As Jon says its a 23d4, no vacuum advance because of the cam characteristics (long duration and poor vacuum signal) so if the Simonbbc unit fits, then just swap it over, if not then contact him for one to suit the 23d4 :)

4650583641_dba2503b41_o.jpg

"You,re only supposed to blow the bloody SLIDING doors off"
 
your advance curve is controlled mechanically by the bobweights and springs inside the dizzy ;)

4650583641_dba2503b41_o.jpg

"You,re only supposed to blow the bloody SLIDING doors off"
 
Cheers guys, really appreciate the useful input

I dragged out the Hunter WM last night before I'd read your responses, which lists the dizzys for Hunter GLS / Holbay engine as ;

Dizzy : Application no
Lucas 23D4 (no VA) : 41239
Lucas 43D4 (no VA) : 41454 or 41556
Lucas 45D4 (VA) : 41604

The first 2 make sense as my understanding is that the 43D4 is bascially a more compact, reliable and better performing replacement for the 23D4 (as per 25D4 / 45D4 comparisons but without vacumn advance).

What's thrown me is the 3rd option of a 45D4 which does indeed have vacumn advance. Apparently this was a later configuration for the Holbay engine - which perhaps suggests it was introduced as either an improvement or cost saving measure [?]

HolbayLogo.jpg

'Hunny' our Commer Hi-Tor by TorCars
 
My further research has suggested that the non-vacumn advance option was used on setups with twin Weber 40s as these are without VA. I've still not identified how/why the 45D4 was also used though ...

As I'm planning to use Weber 32/36 on a modified Solex manifold, the later caters for VA - I'm now wondering whether I can simply swap my almost new SimonBBC 45D4 from the Commer 1725 over to our Holbay ?

If I'm correct this should work OK but possibly not optimum but to get the correct 41604 setup for the 45D4, would this just be a case of obtaining the correct springs to convert to Holbay advance curve spec ? Is anybody able to confirm please ?

Also found this handy PDF for lookup of dizzy and service no. for loads of classics which might be useful to others ;

http://www.mgaroadster.co.uk/Technical_Information/lucas.pdf


HolbayLogo.jpg

'Hunny' our Commer Hi-Tor by TorCars
 
Paul, your 45d4 will be a straight swap, so no problem there :)
As for the advance curve, yes changing springs and/or bob weights will alter it, but its quite probable that the Holbay curve will be wrong too, as your set-up is with different carbs/manifold. so the chances of the Holbay curve being correct are about the same as for the one in your 45d4.
best option is to fit the 45d4, try it, and then try swapping springs etc to see if there is any improvements ;)

4650583641_dba2503b41_o.jpg

"You,re only supposed to blow the bloody SLIDING doors off"
 
I think - might be wrong - that some of the later hillman hunter GLSs fitted with holbay engines had twin strobie 175s rather than webbers.

I suspect the differences in advance curves will make very little difference in actual performance. I agree with commeracer that you're best using your almost new electronic 45d4 - this is likely to give you better results than a less than new orginal holbay item.

m_5ab8dd55b2c2c84c5ce92d6090469c78.jpg
 
Originally posted by Paul Goldsmith




As I'm planning to use Weber 32/36 on a modified Solex manifold, the later caters for VA - I'm now wondering whether I can simply swap my almost new SimonBBC 45D4 from the Commer 1725 over to our Holbay ?



We tried fitting this carb on riches dodge van (steve williams) with the holbay in and you need to do majour mods to the engine lid and engine cover plate under the passenger seat,to the fact that the passenger seat will not sit correctly on the floor.

When you say your modding the manifold,What are you doing just expanding the venturi ports in it for the carb to open and close correctly?[?][?]
 
Thanks for all the dizzy info folks, really helpful and good to know I could save some £££'s by reusing my existing SimonBBC dizzy ;)

Jon, thanks (I think :() for the update re. fitment to the Dodge van - last update I had from Steve/Rich was that it hadn't been tried yet but was looking tricky. I was planning a setup based on this Sunbeam - would this offer any benefits to the Commer fitment issue in your opinion ?

sunbeam_weber03.jpg


To answer your manifold question, definately the porting to allow for Weber operation - this has been sent to Tim and he's said he'll take a look to see if there are any options to pursue further - would be interesting to feed in your own detailed findings, just in case ...

If not, then it's either twin SU HS4s or twin Strombie 150's which I've got in the garage (with manifolds) - just depends which are in best nick (SUs preferred) !

BTW : Which waterpump housing and pump unit did you use on your Holbay installation [?] As that's my next focus, also planning to ditch the fan for a leccy one only.

HolbayLogo.jpg

'Hunny' our Commer Hi-Tor by TorCars
 
Wahey Steve - so the dream might still be on :D

Here you go Renaultvation, cast your peepers over these ;)

sunbeam_weber02.jpg


sunbeam_weber03.jpg


If you're interested further, here's the source of my 'inspiration' from the Sunbeam Alpine OC ;

http://alpine.forumup.com/about664-0-asc-0-alpine.html

The SAOC have also dug up an original Rootes commission DGV inlet manifold which is now being actively pursued for remanufacture :p:p ;

http://alpine.forumup.com/viewtopic.php?t=1039&highlight=weber&mforum=alpine

With a brand new jetted Weber DGV 32/36 around £170 all in, if this set up works on the Commer with Holbay it could just be the bargain of the year ;)

HolbayLogo.jpg


'Hunny' our Commer Hi-Tor by TorCars
 
Jons not confused lol! There just is not enough space using this manifold which is the one we tried with the 28/36dcd the actual carb body sizes look the same from your pics. I think you would be much better using a side draft option as there is far more room if you take the shelf out as steve has. Then you can keep all the engine lid and seat mounts standard.The space is that tight you even have to move the oil filler neck on the rocker cover as the engine lid will not shut. This rocker cover on your pic would work atreat though you need the filler at the back of the engine.;)
 
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